399425 divided by 87 
The aim is to understand the frequency of 87 in 399425.

Going ahead to step 1:
87 goes into 3 0 times with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 87

Going ahead to step 2:
87 can be fit into 39 0 times, resulting in a remainder of 39.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 39 leaves us with 39.
Grab the next digit (9) from the dividend, add it to 39, then carry on: 399 / 87

Advancing to step 3:
The number 87 fits into 399 4 times, leaving a remainder of 51.
Use 4 as the next digit of our solution. 
Result so far: 4.0
Subtracting 348 from 399 leaves us with 51.
Include the next digit (4) from the dividend after 51, then repeat: 514 / 87

Let's proceed to step 4:
The number 87 fits into 514 5 times, leaving a remainder of 79.
Use 5 as the next digit of our solution. 
Result so far: 45.0
If we subtract 435 from 514, we get 79.
Append the next digit (2) from the dividend to 79 and continue with: 792 / 87

On to step 5:
792 divided by 87 is 9 with a remainder of 9.
Write down 9 as next digit of the result. 
Result so far: 459.0
Subtract 783 from 792 to get 9.
Take the next digit (5) from the dividend and append it to 9, then repeat: 95 / 87

Moving on to step 6:
When dividing 95 by 87, we get 1 with a remainder of 8.
Record the quotient 1 as the next digit in the result. 
Result so far: 4591.0
Subtracting 87 from 95 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 7:
When dividing 80 by 87, we get 0 with a remainder of 80.
The number 0 becomes the next digit in our result. 
Result so far: 4591.0
The remainder is 80 after subtracting 0 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 8:
800 divided by 87 is 9 with a remainder of 17.
Write down 9 as next digit of the result. 
Result so far: 4591.09
Subtract 783 from 800 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 9:
87 can be fit into 170 1 times, resulting in a remainder of 83.
Use 1 as the next digit of our solution. 
Result so far: 4591.091
Deduct 87 from 170 and we're left with 83.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

Moving on to step 10:
When dividing 830 by 87, we get 9 with a remainder of 47.
Record the quotient 9 as the next digit in the result. 
Result so far: 4591.0919
Deduct 783 from 830 and we're left with 47.
Since there are no more digits in the dividend, we add a zero to the remainder making it 470, and continue the process.

On to step 11:
87 goes into 470 5 times with a remainder of 35.
Record the quotient 5 as the next digit in the result. 
Result so far: 4591.09195
If we subtract 435 from 470, we get 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Going ahead to step 12:
350 divided by 87 is 4 with a remainder of 2.
Use 4 as the next digit of our solution. 
Result so far: 4591.091954
The remainder is 2 after subtracting 348 from 350.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Advancing to step 13:
20 divided by 87 is 0 with a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 4591.091954
If we subtract 0 from 20, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 14:
When dividing 200 by 87, we get 2 with a remainder of 26.
The next digit of our result is 2. 
Result so far: 4591.09195402
If we take 174 away from 200, we end up with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

The final result is 4591.09195402 with a remainder of 2.6e-08.